The present invention relates to a method and an apparatus for the injection of ultrasound into tissue parts to be treated, using ultrasound pulses.
In medical technology, ultrasound is used on the one hand as a diagnostic aid for imaging processes, and on the other hand is also used therapeutically. Ultrasound produces density waves in the tissue, which act as vibration and as heat. Ultrasound injection thus on the one hand achieves a mechanical effect which acts like micromassage in soft-tissue, and in the process, for example, stimulates the release of tissue hormones and influences the metabolism and muscle state. The stimulating effect of this mechanical component of therapeutic ultrasound can have a positive influence on tissue regeneration. The thermal component of the therapeutic ultrasound leads to tissue heating which is used, for example, during thermotherapy.
Therapeutic ultrasound is used both continuously and in pulse form. In the case of continuous injection, a suitable oscillation generator continuously produces ultrasound waves at a predetermined ultrasound frequency. In the case of pulsed ultrasound, pulses of ultrasound are produced. These pulses of ultrasound then have a pulse width or pulse length in the time domain, while the ultrasound is injected at the respective ultrasound frequency.
This is followed by a time interval with an injection pause, in which no injection whatsoever takes place. The number of such ultrasound pulses per unit time results in a pulse repetition frequency. The limit case of injection pauses turning to zero results in continuous ultrasound.
The therapeutic effect of the injected ultrasound in this case depends in particular on the selected ultrasound frequency, the duration of application, and also on the nature of the injected ultrasound pulses. By way of example, possible pulse parameters are the pulse width, the pulse length, the ultrasound frequency, the amplitude of the ultrasound and the pulse repetition frequency. The person carrying out the therapy has to in this case decide what power and in what signal form the therapeutic ultrasound must be used, and in some cases this is difficult to assess. Precise setting of the treatment depth in a tissue by ultrasound application is also frequently difficult.
Proposals have already been made in the past to inject ultrasound energy at different ultrasound frequencies from a plurality of ultrasound transmitters at the same time into a tissue that is to be treated. Published German application for patent No. 103 06 795 A1 discloses a corresponding ultrasound device in which a plurality of ultrasound beams at different frequencies act at a common focus area in the tissue at the same time. However, this results in the disadvantage of a high level of implementation complexity with a plurality of ultrasound sources and operation by the person carrying out the therapy, who must himself define a large number of parameters, such as the frequency, pulse lengths and injection power.